Diaphragm device



Dec. 18, 1934. E H: FOLEY Er AL 1,984,637

DIAPHRAGM DEVICE Original Filed April 29, 1925 36w GUI B. swim/ EARL, H.FULE'K Patented Dec. 18, 1934 DIAPHRAGM DEVICE Earl H. Foley; Seattle,and Guy B. Sampair, Tacoma, Wash, assignors, by direct and mesneassignments, to Filmtone Corporation, a corporation of DelawareApplication April 29,

1925, Serial No. 26,797

Renewed May 12, 1934 2 Claims.

Our invention relates broadly to improvements in sound recording andreproducing instruments of the diaphragm type, and more particularly itis our purpose to provide a device of this character wherein means areemployed of a unique nature for intensifying the action ofa diaphragmupon a stylus under the influence of sound waves directed thereupon.

Heretofore, in devices for recording and reproducing sound'of the typewherein a diaphragm has mounted thereon a cutting stylus, it has beenusual to mount the stylus at the central point of the diaphragm. When somounted, however, it has been found that the relatively high degree ofresistance offered by the recording medium or record body to themovement of the cutting stylus when actuated by the vibrations of thediaphragm serves to dampen the movement of the diaphragm at the point ofcontact of the stylus with the diaphragm thereby allowing a largeproportion of the force of the sound vibrations to be dissipated throughthe elasticity which exists in the unsupported portion of the diaphragmbetween such central point whereon the stylus is mounted and theperiphery supported by the diaphragm housing. In our present invention,however, advantage is taken of the movement of that portion of thediaphragm between the central portion and the periphery by providing aplurality of points of contact between the cutting stylus support andthe diaphragm, thus greatly reducing the unsupported area of thediaphragm and hence greatly reducing the elasticity and consequentmovement of what has heretofore been the unsupported portion, and at thesame time transmitting a far greater force to the cutting stylus than isthe case where only one point of contact between the stylus and thediaphragm is employed. Experience has demonstrated that the best resultsare obtained with the conventional type of recorder when the diaphragmused has a relatively small diameter; this being due to the fact thatthe unsupported area of the diaphragm is thus reduced and thedissipation of movement of the diaphragm through the elasticity of theunsupported area thereof curtailed. At the same time with diaphragms ofsuch a relatively small diameter, there is encountered the decideddisadvantage of the lesser movements of the smaller diaphragm when actedupon by sound waves, thus rendering more feeble the action of thecutting stylus and limiting the type of effective recording material tothat of a relatively soft and plastic nature. In our present improvedrecorder a diaphragm of an area many times that which has beenheretofore thought possible is employed, thus greatly intensifying themovements of the cutting stylus and permitting clear and accuraterecording of sound on materials which have previously been consideredtoo hard.

To these and other equally important ends our invention consists in theconstruction, combination and arrangement of parts describedhereinafter, but interpretation of the scope of the invention shouldonly be conclusive when made in the light of the subjoined claims.

One embodiment of our invention, and several minor modifications thereofare represented by way of example in theaccompanying drawing, wherein;-

Figure 1 is a bottom plan view of a diaphragm provided with our fourpoint spider,

Figure 2 is a sectional side elevation, the device being inverted, ofthe type of recorder having a spider such as is shown in Figure 1,

Figure 3 is a view similar to Figure 2 of the four point spider type,but the stylus carrying member is here of a slightly modified form,

Figure 4 is a view of a preferred type of diaphragm casing which isadapted to insure a greater constancy in pressure on a recording medium,

Figure 5 is a side elevation, partly broken away, showing a modifiedform of stylus carrying member, and

Figure 6 is a top plan view of a modified form of stylus supportingspider having eight points.

Like characters of reference are used to designate like or similar partsin the several views of the drawing, in which;

The diaphragm casing is designated (1) and is circular in configuration,and annularly flanged as at (2). Centrally of the casing is provided aflanged opening (3) through which the sound impulses or waves aredelivered.

Mounted on the flanged portion (2) of the casing and secured in place bysuitable gaskets (4) is a diaphragm (5), and carried upon the diaphragmis a spider (6) formed with four radial legs (7) terminating in feet(8). The central portion or crown (9) of the spider is spaced from thediaphragm and in attaching the spider to the diaphragm any suitablecement may be used. An optional form of my spider is shown in Figure 6in which eight legs are used, the alternate legs (7) being shorter.Formed on the crown of the spider is a post (10). The post (10) and thefeet (8) of the legs (7) all contact with the diaphragm and serve toconvey simultaneously from the various areas of the diaphragm themovements of the same under the influence of sound waves deliveredthereto. A stylus (11) is mounted on the crown (9) and extends angularlytherefrom into contact with a record body (not shown). Obviously thedevice may be utilized with equal facility either to record or reproducesound but in the present instance it is believed that a detaileddescription of the process of recording will sufiice.

In Figure 3 of the drawing is illustrated a modified form of mountingthe stylus in which lever action is utilized to increase itsefiectiveness. In this form an arm (12) is pivotally attached as at (13)to the crown (9) of the spider (7) and midway of its length it isfulcrumed as at (14) on a post (15) carried by the flanged portion (2)of the casing. The stylus (11) is carried on the free end of the arm. InFigure 4 an optional form of diaphragm casing is shown, and such formexemplifies the use of an interior supplementary casing member (16)which carries the diaphragm, and which is spaced from and chambered inthe exterior casing, and connected thereto by a suitable hinge (17) sothat a constant pressure may be exerted upon a record body during theproduction (or reproduction) of a record. The form of casing may be usedwith any of the embodiments of my diaphragm or stylus carrying member.

In Figure another modified form of stylus carrying member is shown inwhich lever action is utilized; Here the arm (18) is pivoted to thecasing as at (19) and fulcrumed on the crown of the spider as at (20),and is formed with a plurality of longitudinally aligned, spaced,screwthreaded openings (21) in any of which the angular stylus carryingmember (22) may be placed for retention. The movement of the stylusunder the influence of the diaphragm is obviously inverselyproportionate to the distance of the member (22) from the free end ofthe arm, and directly proportionate to its proximity with the pivotedend (19) of the arm.

In operation, sound waves are introduced into the casing through theopening (3) therein by means of the usual tube or horn (not shown);these waves strike the diaphragm (5) causing it to vibrate; thevibrations are transmitted to the legs of the spider (6) and thus imparta vibratory movement to the cutting stylus through crown (9). Thismovement is of course translated into a record groove in any suitablerecord material which may be passed beneath the cutting stylus. Whetherthe record grooves designed to be out are of the vertical or horizontaltype is immaterial since my device will out either kind with equaleffectiveness and upon material of any reasonable hardness. In the eventthat it is desired to reduce the extent of movement of the stylus underthe influence of the diaphragm, or increase the magnitude, this can beaccomplished by varying the position of the stylus carrying member (22)on the arm (18). It has been found that our present recording diaphragmwill function with materials of great hardness, and the simplicity ofthe device as a whole commends it.

While in the foregoing there has been illustrated and described suchcombination and arrangement of elements as constitute the preferredembodiments of our invention, it is never.- theless desired to emphasizethe fact that interpretation of the invention should only be conclusivewhen made in the light of the subjoined claims.

Having described our invention and its objects with such attention todetail as will thoroughly acquaint one skilled in the art with itsconstruction and advantages, we claim:

1. In a sound recorder, the combination of a housing, a diaphragmmounted therein, a cutting stylus, a cutting stylus carrying memberhingedly mounted on said housing, said member having a plurality ofpoints whereon said cutting stylus can be mounted, means forcommunicating movements of said diaphragm to said stylus carryingmember, said means having a plurality of points of contact with saiddiaphragm.

2. In a sound recorder the combination of a support comprising ahousing, a large diaphragm mounted in said housing, a stylus carryingmember hingedly mounted on said support, means connected to one point ofsaid member for communicating movements of said diaphragm to saidmember, said means having a plurality of points of contact with saiddiaphragm, a cutting stylus secured to said member at a point closer tothe pivotal support of said member than the said one point and saidmember having means located at a point differently spaced from saidpivotal support for securing a stylus thereto.

GUY B. SAMPAIR. EARL'I-I. FOLEY.

